"Speaking to our captains and the coast guard, this is the worst ice they've seen in decades," said Marine Atlantic spokesperson Darrell Mercer. "Weather conditions this winter has made for a difficult season."

Mercer noted that vessels have been impacted in the Gulf of St. Lawrence, especially off the coast of western Newfoundland, adding that according to the Canadian Coast Guard, some of their ice breakers are having issues."

There are concerns that ice currently off western Newfoundland is going to eventually make its way into the Cabot Strait.

"Our captains are already saying the ice is fairly persistent as they make their crossing, and in some situations have chosen an alternate route because the ice moved that much in 12 hours.

"We are concerned that if the winds change, especially to a northeast direction, that will push the ice into Sydney harbour."

Sydney harbour has a history of layering, when the ice overlaps, it goes further down in the water creating a wall of ice.

Once that happens it is difficult for vesels to get through.

"We want to give customers and passengers some advance notice that these ice conditions are in the gulf," Mercer explained. "While these conditions aren't impacting our schedule to any degree at this point, there is the potential. Depending on weather conditions, it (ice) could eventually come into the Cabot Strait and potentially have an impact on our sailing schedule."

He said all Marine Atlantic’s vessels are ice class and can work through significant ice.

“Our captains are experienced in working through ice conditions and our vessels are manoeuvreable in ice."

Marine Atlantic pays a fee to the Canadian Coast Guard to ensure the ferry service is a priority.

"We are in constant contact with the coast guard to ensure they have all the information regarding our needs."

Referring to the weather over the past few years, Mercer said conditions been fairly good and ice hasn't had much of an impact on the ferry service.

“But a lot of people are saying this is the worst ice they’ve seen in decades, so it is something we are keeping a close eye on.

"It’s not only our captains and employees and the coast guard who have been saying the ice conditions are really thick. We’ve heard from other mariners, fishermen who in the past 20 or 30 years haven’t seen ice like this so there is cause for concern."

In March 2009, 170 passengers spent four days on board the former MV Caribou which was stuck in pack ice off Sydney harbour.